Several major cable operators are making new deployments of switched digital video – see here and here – which provides a timely opportunity to explain how SDV works and how consumers will benefit. Standard cable service, both analog and digital, works on a “broadcast” model, in which every available channel is sent to every subscriber all of the time, regardless of what is actually being watched. Sending more channels than you're actually watching just takes up more of the capacity on the cable pipe – capacity that could be used for other important purposes. As this article succinctly puts it:
One of the primary benefits of SDV is that it frees up bandwidth because it only delivers the channel a customer is viewing.
In previous posts – like this one on net neutrality or this one on consumption-based billing – we’ve referred to the competing demands on network bandwidth. Your local cable system has a finite amount of capacity over which to provide all of the voice, video, and data services that its consumers demand. A tool like SDV is one method of clearing up bandwidth for other services, allowing your cable provider to offer faster broadband speeds, more HD and niche programming, and other new services. That’s why the FCC has endorsed cable’s use of SDV (For example, see this FCC Order regarding deployment of SDV by Cox and Time Warner Cable.). Other multichannel video providers use SDV, including AT&T’s U-verse service, which is 100% switched digital.
Two-Way Services Need Interactivity
Some people want to receive digital cable service with devices other than a cable-provided set-top box, such as a TiVo DVR. For purposes of authentication, a CableCARD needs to be used as part of that connection. You can read this blog post to get the background on CableCARDs, but the salient detail here is that the 2002 agreement between the cable and consumer electronics industries that led to CableCARDs only covered devices that receive one-way cable services, such as the channels that are continually “broadcast” on the cable pipe without anyone actually requesting them. These one-way devices are known by the long – yet descriptive – name “Unidirectional Digital Cable Ready Products.” UDCPs were never designed or intended to be able to receive Video-on-Demand, electronic program guides, and other two-way services that require interaction between a set-top box and the cable operator’s plant – and the FCC required UDCP manufacturers to expressly warn consumers of those limitations. Based on the description above, you might easily surmise that SDV requires interactivity. A channel request goes up the line to your cable provider, and then the requested content is sent back. Even though UDCP devices were never intended to receive content delivered over a two-way platform, the cable industry and TiVo worked together to develop a solution for consumers who were using TiVo UDCP devices on systems where some channels were delivered using SDV. That solution is called a “Tuning Adapter,” because it is a device that connects to a consumer’s TiVo box and provides the two-way functionality to request (or “tune” to) SDV content. A TiVo press release (NCTA and TiVo Announce Switched Digital Solution for HD DVRs) and this 2007 news story (TiVo, NCTA Team Up on Switched Digital) outline the joint development.
In April, the FCC launched two proceedings about video devices, one of which asked questions about whether Tuning Adapters are working. Although TiVo’s website asserted that the Tuning Adapter “works well” for accessing SDV content (TiVo’s website declared “there are no known issues with Tuning Adapters and Premiere/XL, TiVo HD/XL, and Series3 HD DVRs”), TiVo is now proposing that the FCC mandate a completely different solution. Or as Todd Spangler put it in Multichannel News, TiVo wants to replace “the Tuning Adapter that cable developed in conjunction with TiVo.” My next post will look into just that issue.